The present invention relates to robotics systems for use in automated laboratory applications, and more particularly to a method and apparatus for the automated determination of total suspended solids (non-filterable residue) in water and waste water.
Automation in analytical laboratories is not, of itself, a new concept, but instead has been widely practiced for many years. More recently, it has appeared mainly in the form of microprocessor controlled analytical instrumentation with dedicated hardware, such as auto samplers, continuous flow systems, and computerized data collection, calculation, and report generation facilities. The very recent past has seen important improvements wherein laboratory automation has been extended by the use of robotics, combined with programmable computers, to new tasks which include sample preparation, and even entire analytical determinations. The first such robotic system was introduced in 1982 by Zymark Corporation (Hopkinton, Mass.). As experience has been gained with these systems, they have been successfully applied to ever more sophisticated laboratory operations.
An example has to do with the filtration of liquids, and in particular the filtration of a sample through an extremely fine filter for measuring suspended solids. Environmental Protection Agency requirements, such as in the EPA approved protocol specified in the manual procedure US EPA method 160.2 for the determination of total suspended solids (TSS) in water and waste water is routinely performed at many manufacturing locations throughout the country, and in support of waste water treatment research and development studies. It is a routine EPA test procedure that is highly repetitive, usually involves a large number of samples to be analyzed, and requires the committed attention of the human analyst--a prime example of a procedure wherein robotic automation would be highly desirable.
Although the repetitive nature of the procedure and the large number of sample analyses typically performed made the total suspended solids analysis a good candidate for automation, it was discovered that such a robotic procedure involved a much more complex system than commercially available. Although the procedure involved sample preparation steps which had already been successfully performed by other laboratory robotic systems, it also included operations that required robot-friendly modules and sensors, and procedures for their exploitation, which were not yet commercially available. In other words, while the procedure was well established for manual execution by a human operator, its automation in a robotics environment was found to be beyond the state of the robotics art.
A need therefore remains for an automated method and apparatus for determining total suspended solids in liquids, and particularly for such a method which can be implemented on a robotics system in a robot-friendly manner in order to substantially eliminate the performance of the repetitive steps by hand. Such a method should be highly accurate, efficient, reliable, repeatable, non-intrusive, non-invasive (to prevent contamination), and sufficiently economical to lend itself to widespread utilization in such analyses.